(57) The present invention discloses a data acquisition apparatus for use as a diagnostic tool in isolating the cause of chronic dropped telecommunication calls. The apparatus monitors electrical signals associated with multiple telecommunication trunks. It recognizes each occurrence of a terminated call based upon loop current cessation of a duration greater than a pre-determined time interval. Each occurrence of a terminated call, as well as electrical data indicative of which equipment terminated the call, is time-stamped and recorded. The apparatus also time-stamps and records data regarding additional electrical events based upon pre-determined ranges of current and voltage. It creates a chronological log of the recorded data. The apparatus interprets the recorded data and provides an easily intelligible message indicating which equipment terminated a particular call. The recorded data and the messages can then be conveniently analyzed by technicians or other personnel on a display screen to determine which equipment dropped a call and to identify significant trends regarding dropped calls. The apparatus functions in a manner that is transparent to a customer so that it does not interfere with the customer's usage of the equipment being monitored.